Interesting question

VR3VR3 Posts: 23,422
So...my brain is racking a question

I am planning on adding two more in ceiling speakers to the mix... And I originally didn't plan this... Haha... But I have a 4 conductor wire ran to my center channel currently

If... A receiver is common ground and all of the negative sides of the speaker terminals across all 7 channels are wired together.... Ie common ground

What would in return stop me from utilizing the 4 conductor wire, 3 as the individual positives and then having a shared ground among all three speakers...

What am I missing that would prevent this from working?

Lol
- Not Tom

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Comments

  • VR3VR3 Posts: 23,422
    edited November 2018
    Just in case my rambling didn't make sense

    And... Would I even need jumpers at the receiver end on the negative side...

    y9jilv0gf3s3.jpg
    - Not Tom

    Vr3Mods.com ///// Version3Audio.com

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • gmcmangmcman Posts: 1,488
    edited November 2018
    Reaching slightly above my pay grade...but I'm going to speculate it wouldn't work as you intended as I believe the amplifier outputs AC voltage to your speakers...if I'm not mistaken.

    I imagine you would get sound, but not in a divided manner with accurate stereo separation....again, only speculation.

    Very curious myself
  • VR3VR3 Posts: 23,422
    edited November 2018
    But if all of the grounds are tied together anyways... It shouldn't matter... Right??

    Need to try this out on a junk Amp

    This is actually kind of how sda works as Polk is using the ground to complete the circuit... Hmmmm

    Maybe @KennethSwauger would have some thoughts 😜
    - Not Tom

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  • FestYboyFestYboy Posts: 3,698
    It works in car audio.... Just sayin'
  • VR3VR3 Posts: 23,422
    So, I really don't see why this wouldn't work...

    With no speakers connected to any binding post, all negative binding posts show continuity - 0 volt and sound passage on the meter... all of the positive terminals are isolated...

    So technically, I should not even need jumpers at the negative binding post.... hmmmmmmm
    - Not Tom

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  • afterburntafterburnt Posts: 5,599
    What are you missing? My guess is a few cards and a brick.
  • VR3VR3 Posts: 23,422
    I tested it on a different Yamaha receiver...

    Simply plugged the left speaker negative into the right speaker negative... Works perfect... Will leave it running for a while to see if anything adverse happens but so far... No issues
    - Not Tom

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    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • ambiophonicsambiophonics Posts: 659
    edited November 2018
    I would think if you're not running very high power it would work fine, you've already confirmed the receiver is common ground. With enough power the wire gauge of the single ground might become a bottleneck to good sound but I don't see any big issues with doing this.
    2 Channel - Polk SDA-2BTL full upgrades, Carver TFM-35, Peachtree iDAC, Chromecast Audio (optical), Bugle II phono pre, Technics SL-1500 w/ M97XE
  • VR3VR3 Posts: 23,422
    edited November 2018
    That is the one concern I had, the ground would be shared to a 10 foot or so 13 awg wire, so it is still a good thickness over a relatively short distance. The speakers they would be pushing would be crossed at 80hz, maybe 60hz...

    Appreciate the input

    This will save a substantial amount of time. And money plus simplify the entire wiring scheme
    - Not Tom

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  • mrlorenmrloren Posts: 2,077
    I don't know about the electrical of this but I do have another view on it.

    Coming from manufacturing for 17 years. Designers and engineers look for every way to save on everything. If they could eliminate 6 of 7 binding post they would do it. If it was totally possible they would have made that change long ago.

    Why risk your equipment spend a little extra time and run the wire.
    When I was a kid my parents told me to turn it down. Now I'm an adult and my kids tell me to turn it down.

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  • VR3VR3 Posts: 23,422
    I understand that perspective, but what they save would also create an incredibly unfriendly setup for the end user... People can barely hook up an aux cord to. Their phone much less a home. Theater.

    I think from a wiring standpoint, this is a sound arrangement... I'll know by end of this weekend!
    - Not Tom

    Vr3Mods.com ///// Version3Audio.com

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • mdaudioguymdaudioguy Posts: 5,082
    I'm very interested to hear how this works out.
  • VR3VR3 Posts: 23,422
    So... Unfortunately usps let me down and didn't deliver my caps. And resistors as they said they would...

    However I did get alot accomplished... I changed out all of the internal wiring and prepped everything for the new parts...

    I cut the holes in the ceiling and ran the wire...

    I did a simple meter test and everything registers Perfect. With a single lead going back to negative at the receiver, no jumpers, all channels register continuity at their appropriate negative even though nothing is plugged in there....

    Should work perfect...

    Will update whenever the usps starts delivering on their promises lol
    - Not Tom

    Vr3Mods.com ///// Version3Audio.com

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • VR3 wrote: »
    But if all of the grounds are tied together anyways... It shouldn't matter... Right??

    It depends on the design of the amplifier.
    VR3 wrote: »
    This is actually kind of how sda works as Polk is using the ground to complete the circuit... Hmmmm

    You may recall that it was discovered that SDA speakers sound better when using the Dreadnought AI-1 non-common ground interface with common ground amplifiers. This is because the Dreadnought provided another layer of isolation from the amplifier's ground plane noise.

    Since all the electrical components in an amplifier dump noise into the signal ground plane, you want the ground plane to be as large as is practical. It is analogous to diluting poison in a pool of water. The larger the pool, the greater the dilution.

    In a common ground stereo amplifier, buffering and other types of filtering can be used to provide each channel with additional isolation from the ground plane noise, even though there is an electrical connection to ground.

    The ground wire running to each speaker is an extension of the amplifier's ground plane. By running three speakers from a single ground wire connection, you would effectively be reducing the size of the ground plane, and you would be bypassing the ground plane noise isolation schemes of the other two channels, thereby making each speaker and amplifier channel more susceptible to the noise generated by the other speakers and amplifier channels. This noise will increase as more demands are placed on the amplifier. Whether this noise is audible or objectionable to you is another question.

    You should compare the sound with individual ground wires and with one ground wire to see if you hear a difference, particularly with bass heavy and with louder playback levels.



    "So hot it burns Mice!"~DK
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  • VR3VR3 Posts: 23,422
    That's makes sense and I think I can tolerate that with this setup

    My end goal with this configuration is to isolate my HT from 2 channel... I want it to where my wife can tap into the HT for background musi, mains crossed at 80hz, sub takes over rest... And the 2 channel would be completely independent...

    So this is a non critical listening rig, just HT and around the house music
    - Not Tom

    Vr3Mods.com ///// Version3Audio.com

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • VR3VR3 Posts: 23,422
    edited December 2018
    So post office dropped off the caps and resistors... Quickly thew it all together, wired her up... Ran calibration, perfect left right and center on the calibration... No issues
    sounds great...

    Side comment, I put all of the connections in a weather proof j box...

    Quick and easy project with some minor install headaches.
    - Not Tom

    Vr3Mods.com ///// Version3Audio.com

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • mdaudioguymdaudioguy Posts: 5,082
    So, you spliced one negative to three speakers, and positive from three receiver channels to three speakers? Center, and are the two additional Atmos channels?
  • VR3VR3 Posts: 23,422
    From the receiver there are four conductors...

    Ie....

    Blue, left positive
    White, right positive
    Red, center positive
    Black, negative

    From the left speaker, I ran a normal positive and negative to the center speaker, here the grounds joined. Same from the right speaker.

    So the center, left and right share one ground, but of course it is important that you connect each speaker to ground.

    I am using it currently for left right and center but I could use them as atmos heights in the future if I wanted to.
    - Not Tom

    Vr3Mods.com ///// Version3Audio.com

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • mdaudioguymdaudioguy Posts: 5,082
    Gotcha. Interesting for sure. Thanks for posting!
  • mhardy6647mhardy6647 Posts: 22,941
    Now I am confused. :|

    @VR3, if you get bored, can you put together a little wiring diagram (including connections to the amplifier outputs)? :)

    I haven't been following this closely, but my sense of this thread had been tying the grounds together... but the post I just read (i.e., as I read it) makes it sound like some channels are paralleled? I can't imagine that's the case, but I am too much of a visual learner to glean the wiring from words :(

  • mhardy6647mhardy6647 Posts: 22,941
    edited December 2018
    oh, wait - this is (stilL) what you did?

    y9jilv0gf3s3.jpg

    I guess two thoughts/questions pop to mind.

    1) if the grounds (returns) are all common for all three channels, is there any need to tie them together at both ends?

    2) Does this configuration still provide three distinct channels, or does it blend them together?

    I am -- just not sure. :)

  • VR3VR3 Posts: 23,422
    This is what I did, ultimately did not run any jumpers at the receiver negative, just a single conductor back into the left channel ground.

    This does provide 3 distinct channels but I could not use separate amps unless the separate Amp had a similar shared ground.

    dkd7bxvp6bxx.jpg
    - Not Tom

    Vr3Mods.com ///// Version3Audio.com

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • mhardy6647mhardy6647 Posts: 22,941
    It is interesting, indeed. Makes one wonder why it's not done more often -- are "we" missing something? :)
  • VR3VR3 Posts: 23,422
    I really think it is done for simplicity (the traditional way) , in the short bit I listened, there was nothing adnormal or anything to spark concern.

    Plus, in this configuration I could never run a 2 channel Amp, it would have to be a 3 channel amp with a common ground. So there are limitations in this arrangement but it works for my use! Saved me alot of money in wire and time!
    - Not Tom

    Vr3Mods.com ///// Version3Audio.com

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • RobbyKYRobbyKY Posts: 104
    A little late but do remember our good friend Mr. Kirchhoff and his very firm laws. For current, what goes out must come back. By connecting all the grounds through a common conductor you need to sum the currents supplied by each channel and decide if your wire gauge is good. If all three channels supply, say 40 amps each, then that one common ground wire will see 120 amps. Of course music is dynamic and no one blast a constant high current level but the laws must be obeyed.....
    SDA SRS 1.2TL x2 - SDA SRS 3.1 x2 - SDA 2BTL
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  • VR3VR3 Posts: 23,422
    Watched mission impossible a few clicks from reference levels, all good 😁
    - Not Tom

    Vr3Mods.com ///// Version3Audio.com

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • In the low voltage world of alarm installing it is common and done often to share the common negative for either keypads and motion detectors if short on home runs. I can't see why it would not work on an amp. With that said straight ac devices like amplifiers might or might not like this idea at all. Not advising own risk here.
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